The t-butyl [[2-[[(4-chlorophenyl)sulfonyl]methyl]benzyl]oxy]diphenylsilane (1.00 g, 1.87 mmol) obtained in Example 280 and 5-(t-butyldiphenylsilyloxy)-1-pentanol (0.68 ml, 2.8 mmol) were dissolved in toluene (7 ml), followed by the addition of cyanomethylenetri-n-butylphosphorane (650 mg, 2.69 mmol). Under an argon atmosphere, the resulting mixture was heated under reflux for 14 hours. After the reaction mixture was allowed to cool down, 5-(t-butyldiphenylsilyloxy)-1-pentanol (0.34 ml, 1.4 mmol) and cyanomethylenetri-n-butylphosphorane (300 mg, 1.24 mmol) were added. Under an argon atmosphere, the resulting mixture was heated under reflux for 10 hours. The reaction mixture was then allowed to cool down. The residue obtained by concentrating the mixture under reduced pressure was subjected to flash silica gel chromatography, and the fraction obtained from the hexane:ethyl acetate=15:1 eluate was concentrated under reduced pressure, whereby the title compound (932 mg, 1.27 mmol, 68%) was obtained as a pale yellowish brown oil.
